def get_available(self, product, location, slabs=None):
"""
Args:
product: object产品
location: object库位
slabs: questset板材
Returns:元祖，（件，数量）
"""
return Stock.get_available(product=product, location=location, slabs=slabs)
def get_available(self, location=None):
return Stock.get_available(product=self, location=location)
